1. Field of the Invention
The present invention relates to a sanitary (hygienic) tampon to be inserted into a vagina for absorbing the menstrual blood.
2. Description of the Related Art
In recent years, a variety of products have been developed as the sanitary tampon. In Japanese Patent Laid-Open No. 146548/1989, for example, there is disclosed a sanitary tampon which is constructed to include an absorber made of hydrophilic fibers and an outer layer made of a hydrophobic sheet having hydrophilic fibers mixed therein. In Japanese Patent Laid-Open No. 146058/1991, on the other hand, there is disclosed a tampon which is constructed to include a column-shaped highly compressed core and an outer wall. In Japanese Patent Laid-Open No. 68695/1993, moreover, there is disclosed a tampon in which a sheet of a high fiber density and a sheet of a low fiber density are combined so that the sheet of a low fiber density may partially appear in the surface when the tampon is formed into a column shape. In these tampons, the absorbent fiber material is compressed and formed into the column shape, and this compression is released by absorbing the menstrual blood when the tampon is used. As a result, the tampon swells to close the vaginal opening and absorbs the menstrual blood which is then continuously discharged.
However, the menstrual blood is so highly viscous that it hardly migrates into the central portion of the tampon of the related art but resides on the surface of the tampon. This lowers the absorption rate of the menstrual blood so that the compressed tampon takes a long time to restore its bulk. When much menstrual blood is discharged, on the other hand, it cannot be fully absorbed by the tampon, or the vaginal opening is not fully closed due to the low swelling rate of the tampon. As a result, the menstrual blood may leak. In the tampon of the related art, on the other hand, the menstrual blood hardly migrates into the central portion of the tampon so that the absorber in the central portion is not effectively exploited. Since the menstrual blood resides on the surface of the tampon, moreover, the tampon, when extracted after use, may present such a poor appearance as to make the user feel uncomfortable.
An object of the invention is to provide a tampon which has a high absorption rate and a high swelling rate.
According to a first aspect of the invention, there is provided a sanitary tampon comprising an absorber including an absorbent layer made of an absorbent fibrous material and a hydrophobic liquid-permeable layer covering the absorbent layer, the absorber being formed firstly into a flat shape and then into a column shape, wherein the absorbent layer forming the flat absorber is formed with a plurality of small recesses which open in the surface of the absorbent layer and extend into the absorbent layer.
The flat absorber of the sanitary tampon of the invention is constructed to include the absorbent layer and the hydrophobic liquid-permeable layer on the surface of the former. When the flat absorber is formed into the column shape, however, not only the liquid-permeable layer appears in the column surface but also the surface of the absorbent layer and the liquid-permeable layer enter the inside of the column. According to the first aspect of the invention, moreover, the plurality of small recesses are formed in the surface of the absorbent layer so that they are dispersed and arranged not only in the column surface but also in the inside of the column. As a result, the menstrual blood is not only quickly absorbed from the small recesses opening in the column surface into the inside of the absorbent layer but also introduced into the column through the liquid-permeable layer so that the menstrual blood having penetrated into the column is also quickly absorbed from the small recesses arranged inside of the column into the absorbent layer. On the other hand, even the highly viscous menstrual blood is easily absorbed by catching it in the small recesses. As a result, the absorption rate of the menstrual blood can be raised as the entire tampon so that the tampon can quickly swell to close the vaginal opening.
Preferably, the fiber density of the absorbent layer is higher in peripheral portions of the small recesses than in other portions of the absorbent layer.
Also preferably, the surface of the absorbent layer forming the flat absorber includes upper and lower surfaces, and the small recesses are formed in plurality individually in the upper and lower surfaces. In this case, it is preferable that the small recesses are formed substantially perpendicularly toward the inside of the absorbent layer, and that the fiber density between the small recesses formed from the upper surface and the small recesses formed from the lower surface is higher than the fiber density of other portions of the absorbent layer.
According to a second aspect of the invention, there is provided a sanitary tampon comprising an absorber including an absorbent layer made of an absorbent fibrous material and a hydrophobic liquid-permeable layer covering the absorbent layer, the absorber being formed firstly into a flat shape and then into a column shape, wherein the absorbent layer forming the flat absorber includes upper and lower surface portions and a central portion sandwiched between the surface portions, and the fiber density of the central portion is higher than the fiber density of the surface portions.
According to a third aspect of the invention, there is provided a sanitary tampon comprising an absorber including an absorbent layer made of an absorbent fibrous material and a hydrophobic liquid-permeable layer covering the absorbent layer, the absorber being formed firstly into a flat shape and then into a column shape, wherein the absorbent layer forming the flat absorber includes upper and lower surface portions and a central portion sandwiched between the surface portions, and fibers of the central portion are thinner than fibers of the surface portions.
In the absorbent layer according to the second or third aspect of the invention, the surface portions of a low density or thick fibers has a high permeability for the menstrual blood so that the menstrual blood is easily introduced into the central portion of a high density or thin fibers. This central portion spreads all over the column-shaped tampon, and the central portion is located just inside of the surface of the column-shaped tampon. As a result, the tampon can allow quick penetration of the menstrual blood and can quickly swell to close the vaginal opening.
In the tampon according to the second or third aspect of the invention, it is preferable that in the flat absorber, a region of the higher fiber density or a region of the thinner fibers extends planarly or linearly in a flat direction at the central portion of the absorbent layer. In this construction, in the foregoing region of the higher fiber density or the thinner fibers, the menstrual blood is easily introduced to spread planarly or linearly all over the tampon so that the menstrual blood absorption capacity of the entire tampon can be increased.
In the tampon according to the third aspect of the invention, it is preferable that the fibers of the central portion of the absorbent layer have an average thickness of 0.5 to 3 deniers whereas the fibers of the surface portions have an average thickness of 2 to 6 deniers.
In the tampon according to the second or third aspect of the invention, moreover, it is preferable that the absorbent layer forming the flat absorber is formed with a plurality of small recesses which open in the surface of the absorbent layer and extend so far as the region of the higher fiber density or the thinner fibers in the absorbent layer.